|intra-system, inter-system transport
Rifts are links to distant worlds, distant systems, or something closer like areas on the same world. They serve as a bridge where stepping through one portal takes you to another. The speed of getting from one side to the other is usually very quick. The mechanics of creating rifts, usually by special mines, led to the development of spells like Rift Hop which in turn led to those of teleportation. It does not end their, for Chronos took these, and with his skill with manipulating time, created spells like Time Walk and Haste.
Early in the Dawn Era, the first rift was used to escape the Sea of Entropy. Once on the fringes of the universe's entropic center, building begin, leading to an energy that had long lay dormant, this energy was Negative Entropy. When the Primordial Lords, servants of Chaos, learned of the work of the Creationists, they went to work trying to find them. With distances so vast, rifts that up to then had mostly been seen as conduits of creation, found another use, military highways linking far-flung places. This was the Creation War (1486 DE - 8777 DE), with primordials driven by instinct to end Creation, and reverse the growing strength of Negative Entropy. In the Demon Spawn War, driven by rage, the demons used rifts to invade the Quara'tun System.
Rifts come about from tears in the Web of Magic. This happens from very strong magic being used in an area, prolonged magic in an area, like what happen with the Gulimbor Cataclysm (996 - 1203), or created by something like a Null Mine or Rift Spanner.
Rifts can result in a bleed-over of energies, a movement of energies from one side of the rift to another. Sometimes an area is totally transformed by this, becoming more like what is on the other side of the rift. It is one of the reasons why the sensible peoples of worlds seek to close them and always be on the lookout for them.